Spelt is an ancestral form of wheat, like emmer and einkorn. It was grown widely in Europe until recent centuries, and has been enjoying a resurgence of interest. Its flavor is distinctly different from conventional wheat flour, and those with allergies or sensitivities to modern wheat can often eat spelt. It does contain gluten, however, and is unsuitable for people with celiac disease or gluten allergies. Spelt flour is available in white or "whole spelt" varieties, just as wheat flour is. Spelt flour may be directly substituted for wheat flour in most recipes.
Substitute white or whole spelt flour directly on a 1:1 basis in recipes for biscuits, quick breads and other general-purpose baking. Spelt flour adds flavor and nutrition without requiring any special handling in these instances.
Substitute white or whole spelt flour in bread baking, where its flavor will yield a distinctively different loaf. The gluten in spelt flour behaves differently than that in regular wheat flour, so some recipes will result in denser bread. For a lighter loaf, using a slow-rise bread technique, using bread flour for 1/4 to 1/3 of the total or adding vital gluten are all acceptable alternatives.
Substitute spelt flour directly in cake or pastry baking, on a 1:1 basis. Spelt flour is lower in gluten than all-purpose wheat flour and is appropriate for all but the most delicate forms of pastry. For an especially tender crumb, search out spelt pastry flour. If this is not available in your area or if the price is prohibitive, remove 2 tbsp. of flour from every cup and replace it with cornstarch. This is a standard substitution for cake flour and will give a satisfactory result.
Substitute spelt flour directly, on a 1:1 basis, for making gravy or sauces. As with wheat flour, spelt flour must be simmered for a minimum of 20 to 30 minutes in order to thicken a sauce properly and to eliminate any "raw" taste.